Rotor bearing assembly

ABSTRACT

A bearing assembly for a rotating shaft uses a carbide sleeve to prevent wear and carry load. The carbide sleeves provide increased life for rotating components used in the severe environments in the oil and gas industries. Various mechanisms can couple the carbide sleeve to the rotating shaft, including keys, keyways, drive rings, reaction rings, and other members to provide particular benefits. These mechanisms allow the carbide sleeve to bear the compressive load of other components, for example, or to slide axially on the shaft, when needed.

RELATED APPLICATIONS

This divisional patent application claims the benefit of priority tocopending U.S. patent application Ser. No. 12/643,223, filed Dec. 21,2009, and entitled, “Rotor Bearing Assembly,” which is incorporatedherein by reference in its entirety, and in turn claims priority to U.S.Provisional Patent Application No. 61/140,939 filed Dec. 27, 2008, whichis incorporated herein by reference in its entirety.

BACKGROUND

This section provides background information to facilitate a betterunderstanding of the various aspects of the invention. It should beunderstood that the statements in this section of this document are tobe read in this light, and not as admissions of prior art.

Submersible pumping systems have been employed in the pumping of oil andwater from wells for many years. Commonly, a submersible pumping systemcomprises an electric motor, a motor protector and a pump suspendedcolinearly in a well by tubing or cable. The pump is generally acentrifugal pump which is coupled to the motor. The motor rotates apower transmission shaft that concurrently operates the pump. The motorand motor protector are filled with oil to aid in heat dissipation, tomaintain proper internal lubrication of the motor, and to separate theinternal components of the motor from surrounding wellbore fluids.

Because these pumping systems are generally disposed within a narrowwell, the motor, motor protector, and pump are generally long andcylindrically shaped. The motors vary in horsepower depending on theapplication. Accordingly, the motors of submersible pumping systems canbe quite long leading to particular difficulties not encountered inother electric motor applications.

The motors of submersible pumping systems typically comprise a statorsecured within a tubular housing and a rotor secured to a powertransmission shaft that rotates within the stator. The rotor typicallyis made up of a number of rotor sections, the number of rotor sectionsdepending upon the length and power rating of the motor. Generally, eachrotor section comprises laminated steel plates or disks secured bycopper rods. The rotor sections are spaced apart from each other, and arotor bearing assembly is located between each rotor section. Each rotorsection is connected to the shaft so that all of the rotor sectionsrotate as the shaft rotates.

Each rotor bearing assembly within a rotor section acts to support theshaft and to maintain it in proper axial alignment. A rotor bearingassembly comprises a sleeve connected to the shaft so that the sleeveand shaft rotated together and a journal (e.g., bearing, bushing)disposed coaxially around the sleeve. The sleeve and journal arerotatively coupled to one another. The journal may be configured tofrictionally engage the inner wall of the stator (e.g., housing) toprevent the journal from rotating and to maintain proper alignment ofthe shaft. Thus, a portion of the rotor bearing assembly is rigidlycoupled to the shaft but not to the stator.

Due to the high operating temperatures within the well, thermalexpansion tends to cause the shaft, rotor, and stator to grow axially.Generally, the rotor and shaft tend to grow axially downward during hightemperature operation. The stator also tends to grow axially downward,however, to a lesser extent than the rotor and the shaft. Due to thesethermal expansion effects, the motor is constructed so that each rotorbearing assembly attached to the motor shaft within a rotor sectionoffers a limited amount of axial mobility. Thus, because each rotorbearing assembly is coupled to the motor shaft, the shaft retains thesame limited amount of axial mobility. In some pumps, axial mobility islimited by thrust washers adjacent to each rotor bearing assembly.

Angular misalignment of the shaft within the motor can occur because therotor, shaft, and stator are subject to these dimensional changes due tothermal expansion and because of imbalances in the rotating assembly.Misalignment of the shaft during operation opposes the centering, oraligning force of the bearing assembly and causes vibrations within themotor. Excess vibration can lead to premature motor or componentfailure.

Ideally, the journal remains stationary while the sleeve, rotor, andshaft are rotating. Rotor bearing assemblies have been used in which theperipheral surface of the journal frictionally engages the inner surfaceof the stator through metal-to-metal contact, such as via a metallicwasher. Such metal-to-metal frictional fit rotor bearing assemblies havea tendency to become loose and then to rotate with the shaft. Rotationof the journal tends to gouge and deface the inner surface of thestator. Once the journal begins to rotate with the shaft, the centeringforce of the rotor bearing assembly is diminished leading to increasingangular misalignment, vibration, and motor failure. This type ofconstruction is also unsatisfactory because due to thermal expansion ofthe bearing assembly during motor operation, the journal may tightlyengage the stator wall which can cause angular misalignment of the shaftand thus excessive thrust loads onto the thrust bearing surfacesadjacent to the rotor bearing assembly.

Some electric submersible pumps utilize ceramic carbide (e.g., tungstencarbide, silicon carbide, aluminum nitrite, boron carbide, cobalt)bearings (e.g., sleeve and/or bushing) to resist the abrasive action ofsand or other hard particles in the well fluid and to function with verylow viscosity lubrication. A major challenge with ceramic carbidedevices is securing the mating bearing components in a manner that doesnot create serious stress raisers that make the ceramic carbidesusceptible to cracking. Cracking may be caused by shock loadsencountered during shipping, handling or installation. Cracking may alsobe caused by thermal expansion stresses due to running in a poorlubricant that insufficiently lubricates or cools the bearing, such aslow viscosity fluid or in a well fluid with a high gas content. Crackingmay also be caused by axial or transverse shocks during operation,particularly as the pump shaft constantly moves upward and downwardduring gas slugging. A catastrophic pump failure may occur, if even oneof the cracked bearings (e.g., sleeves) in the rotor (e.g., impeller)stack actually breaks apart.

SUMMARY

A bearing assembly for a rotating shaft uses a carbide sleeve to preventwear and carry load. The carbide sleeves provide increased life forrotating components used in the severe environments in the oil and gasindustries. Various mechanisms can couple the carbide sleeve to therotating shaft, including keys, keyways, drive rings, reaction rings,and other members to provide particular benefits. These mechanisms allowthe carbide sleeve to bear the compressive load of other components, forexample, or to slide axially on the shaft, when needed. This summarysection is not intended to give a full description of a rotor bearingassembly. A detailed description with example implementations follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read with the accompanying figures. It is emphasized that, inaccordance with standard practice in the industry, various features arenot drawn to scale. In fact, the dimensions of various features may bearbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a schematic elevation view of an apparatus according to one ormore aspects of the invention utilized in an electric submersible pump.

FIG. 2 is a cut-away view of a pump motor of an electrical submersiblepump according to one or more aspects of the invention.

FIG. 3 is an enlarged view of a rotor bearing assembly according to oneor more aspects of the invention.

FIG. 4 is schematic illustration of a bearing sleeve according to one ormore aspects of the invention disposed on a shaft between impellers.

FIG. 5A is a schematic illustration of a bearing sleeve assemblyaccording to one or more aspects of the invention attached to a shaft.

FIG. 5B is section view along the line I-I of FIG. 5A.

FIG. 6A is a schematic illustration of another bearing sleeve assemblyaccording to one or more aspects of the invention attached to a shaft.

FIG. 6B is section view along the line I-I of FIG. 5A.

FIG. 7A is a schematic illustration of a bearing sleeve assemblyaccording to one or more aspects of the invention.

FIG. 7B is a sectional view of the bearing sleeve assembly along theline I-I of FIG. 7A.

FIG. 8A is a schematic, end view of a bearing sleeve according to one ormore aspects of the invention.

FIG. 8B is a sectional view of the bearing sleeve along the line I-I ofFIG. 8A.

FIG. 9A is a schematic end view of a bearing sleeve assembly accordingto one or more aspects of the invention.

FIG. 9B is a schematic view of the bearing sleeve assembly of FIG. 7A.

FIG. 10 is sectional view of a bearing sleeve according to one or moreaspects of the invention.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof various embodiments. Specific examples of components and arrangementsare described below to simplify the disclosure. These are, of course,merely examples and are not intended to be limiting. In addition, thedisclosure may repeat reference numerals and/or letters in the variousexamples. This repetition is for the purpose of simplicity and clarityand does not in itself dictate a relationship between the variousembodiments and/or configurations discussed. Moreover, the formation ofa first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed interposing the first and secondfeatures, such that the first and second features may not be in directcontact.

Aspects of the invention relate to rotor bearing assemblies which may beutilized for example in various types of pumps, compressors separatorsand the like. For purposes of clarity and brevity, aspects of theinvention are described generally with reference to electric submersiblepumps and wellbore operations. How to utilize aspects of the inventionin devices (e.g., intakes, pumps, compressors, etc.) other than electricsubmersible pumps will be understood by those skilled in the art in viewof this disclosure.

As used herein, the terms “up” and “down”; “upper” and “lower”; “top”and “bottom”; and other like terms indicating relative positions to agiven point or element are utilized to more clearly describe someelements. Commonly, these terms relate to a reference point as thesurface from which drilling operations are initiated as being the toppoint and the total depth of the well being the lowest point, whereinthe well (e.g., wellbore, borehole) is vertical, horizontal or slantedrelative to the surface.

FIG. 1 is an elevation view of a submersible pumping system disposed ina well and depicted as including a pump module and a motor module. Pumpmodule 2 comprises of a pump 4 and an inducer or intake section 6 forthe pump. Motor module 8 comprises a motor protector 10 and a motor 12.The pump module and the motor module are coupled to one another anddisposed colinearly within a well 14 and suspended at an appropriateposition within well 14 by tubing 16. Electrical power is provided tothe motor by means of a power cable 18. The fluid of interest (e.g.,formation fluid, water, hydrocarbons, etc.) is pumped from the well bythe submersible pumping system to the surface through tubing 16 andthrough well head 20.

FIG. 2 illustrates a submersible pump motor 12 in accordance with one ormore aspects of the invention. The motor is contained within a housing22 into which an electrical connector 24 penetrates for transmittingpower from cable 18 (See FIG. 1). The motor comprises a rotating groupand a non-rotating group. The rotating group includes a powertransmission shaft 26, a rotor section 28 and sleeve 48. The depictedsystem comprises multiple rotor sections 28 and sleeves 48. In thedepicted embodiment, sleeve 48 is constructed in whole or in-part of acarbide (e.g., ceramic carbide), including without limitation, tungstencarbide, silicon carbide, aluminum nitrite, boron carbide, cobalt.

The non-rotating group includes a stator 34 and journal(s) 36. Depictedstator 34 is constructed of metal laminations. Stator 34 may beconfigured with slots running axially through the stator body throughwhich windings 38 run. Each journal 36 is disposed circumferentiallyabout a sleeve 48 and is positioned between stator 34 and the respectivesleeve 48. According to one or more aspects of the invention, each rotorbearing assembly 30 comprises a sleeve 48 and journal 36. Rotor sections28 lie immediately adjacent above and below each journal 36 in theembodiment depicted in FIG. 2.

FIG. 3 is an enlarged view of a portion of a rotor bearing assemblyaccording to one or more aspects of the invention. Depicted in FIG. 3,each rotor section 28 includes a laminated rotor core 40 and a copperend ring 42. Each rotor section 28 has an outer wall 44 which is spacedapart from the inner wall 46 of stator 34. According to one or moreaspects of the invention, sleeve 48 is constructed of a carbide and isrotatively coupled (e.g., attached) to power transmission shaft 26.According to one or more aspects of the invention, the bearing assemblycomprises one or more features to reduce and/or limit the stress raiseron one or more ceramic carbide features of the bearing assembly. Forexample, according to one or more aspects of the invention elements maybe utilized to limit the torque applied to sleeve 48 and/or to limit theaxial or radial load on sleeve 48 relative to a sleeve that does notutilize the features. According to one or more aspects of the presentinvention, the devices rotatively coupling sleeve 48 to shaft 26facilitate providing a carbide cylindrical without a carbidetorque-transmitting feature such as a keyway or the like formed in thecarbide surface of sleeve 48.

Rotor sections 28, while rotatively coupled to shaft 26, are notindividually axially coupled to shaft 26. The lower most rotor sectionat the end of shaft 26 is, however, axially locked to the shaft in orderto support the other rotor sections. Sleeves 48, while rotativelycoupled to shaft 26 are likewise not axially locked to shaft 26. Thus,the rotor sections 28 and the sleeves 48 have a certain amount offreedom to move in an axial direction, i.e., either upward or downwarddue to relative thermal expansion and contraction. In the embodimentdepicted in FIG. 3, an upper edge or circular rim of sleeve 48, or aload carrying portion of sleeve 48, contacts an upper thrust washer 64which is immediately adjacent to the lowermost lamination of upper rotorsection 28. The lower edge of sleeve 48 contacts a lower thrust washer64 which is immediately adjacent to the uppermost lamination of thelower rotor section 28. The thrust washers 64 are constructed of aphenolic laminate. Thus, each sleeve 48 supports the weight of the rotorsection 28 immediately above it and transmits any force from that rotorsection to the rotor section 28 immediately below. As will be understoodby those skilled in the art with reference to the various Figures,sleeve 48 may comprise one or more features to limit the load that isapplied to a ceramic carbide portion of sleeve 48.

The non-rotating group includes stator 34 and journals 36. Each journal36 is disposed circumferentially about a sleeve 48. Thus, where sleeve48 and journal 36 abut one another is a rotating interface 50. Multipleaxially disposed cylindrical passageways 52 through journal 36 providefor oil flow through journal 36 in order that the oil filling the motorcan communicate with adjacent rotor sections for cooling andlubrication.

Journal 36 extends radially outward from sleeve 48 to a peripheralsurface 54. Peripheral surface 54 is slightly spaced apart from theinner surface 46 of stator 34 in the depicted embodiment. Clearancebetween these components is commonly about 0.127 mm to about 0.229 mm(about 0.005″ to about 0.009″). Thus, there is no material-to-materialcontact between journal 36 and stator 34 in the embodiment of FIG. 3.However, according to one or more aspects of the invention as describedwith reference to the figures that follow, journal 36 may be attached(e.g., coupled) to stator 34 (e.g., a housing) for example by a keyextending between peripheral surface 54 and inner surface 46.

In the embodiment of FIG. 3, the outer peripheral surface of journal 36presents a pair of annular support regions 60 and 62. Seals 56 and 58are positioned within circumferential support regions 60 and 62 andfrictionally engage inner surface 46 of stator 34. Circumferentialsupport regions 60 and 62 are preferably spaced apart from one another.In the depicted embodiment a circumferential support region 60 isdisposed adjacent the upper surface of journal 36 and region 62 isdisposed adjacent the lower surface. This spacing of the circumferentialsupport regions, and thus the seals, may provide improved resistance toangular misalignment of the shaft.

FIG. 4 is schematic illustration of a bearing sleeve according to one ormore aspects of the invention disposed between impellers. Features ofthe bearing assembly (e.g., housing, journal) are removed in FIG. 4 todepict the sleeve assembly. In a compression pump, for example, thrustload generated by impellers 100 is transmitted through the stack ofimpellers 100 and bearing sleeves 48 to the thrust bearing in theprotector (e.g., motor protector 10 of FIG. 1). When a sleeve 48 breaksup, the impeller thrust is transferred to the adjacent diffusers whichcan cause rapid wear in the abrasive environment of a wellbore forexample. According to one or more aspects of the invention, sleeve 48(e.g., sleeve assembly 49) may comprise a feature to transfer the axialthrust load across the ceramic carbide portion of the sleeve thereby, ineffect, removing the ceramic carbide sleeve 48 member from the stack forpurposes of the axial thrust load.

Members and/or features of the invention may be utilized in rotorbearing assemblies such as the rotor bearing depicted in FIG. 3 (e.g.,rotor bearing assembly 30 of FIG. 2) as well as other current and priorrotor bearing assemblies. Examples of rotor bearing assemblies utilizedin electric submersible pump systems include those disclosed in U.S.Pat. Nos. 5,795,075, 6,091,175 and 6,424,066 all of which areincorporated herein by reference.

Refer now to FIGS. 5A and 5B which illustrates an embodiment of rotorbearing according to one or more aspects of the invention. FIGS. 4A and4B depict a keyless rotor bearing sleeve 48 (e.g., sleeve 48 does nothave a keyway) which is driven by a drive ring 66. In this embodiment,sleeve 48 is a silicon carbide member. Shaft 26 comprises a keyway 68extending axially along shaft 26. A depression 70 (e.g., dip) may beprovided along a portion of keyway 68 for example to attach the assemblyto shaft 26 for example when keyway 68 does not extend the full lengthand or to a terminal end of shaft 26. Depression 70 may be described isa reduced diameter portion relative to the outside diameter of shaft 26and keyway 68.

In this embodiment, sleeve assembly 49 assembly includes sleeve 48member, a key 72 have opposing tabs 74 (e.g., ears), and a drive ring66. Sleeve assembly 49 may further comprise a reaction ring 76. Drivering 66 comprises a face 78 having a protrusion 80. Protrusion 80 may beformed in various manners, such as and without limitation as a tab, peg,arm or other portion. In the depicted embodiment, face 78 is a contouredsurface (e.g., sinusoidal) which forms protrusion 80. Protrusion 80 isadapted to mate with notch 82 formed along the shoulder 84 of sleeve 48.

The contact between protrusion 80 of drive ring 66 and shoulder 84, forexample at notch 82, of sleeve 48 generates a small axial force thattends to separate the members. Key 72 couples drive ring 66 and sleeve48 and tends to maintain face 78 and shoulder 84 in contact counteringthe separation that may occur for example because of the slack that isprovided to address thermal expansion in the rotor and bearing stack.Reaction ring 76 may be disposed along the opposing shoulder (e.g., end)of sleeve 48 from drive ring 66. Reaction ring 76 and drive ring 66 arecoupled to sleeve 48 via key 72 and opposing key tabs 74. Sleeveassembly 49 provides a mechanism for rotationally locking (e.g.,attaching, coupling) sleeve 48 with shaft 26, so that they rotatetogether, and allow for axial movement relative to shaft 26 for exampleto address thermal expansion. Key 72 and drive ring 66 provide a lockingmechanism that eliminates a need to cut a keyway in sleeve 48 thatcreates an undesired stress raiser. Further, the utilization of key 72,drive ring 66 and optional retainer ring 76 may reduce the axial loadthat is applied to sleeve 48, for example by the rotor sections and/orimpellers. The locking features, for example key 72, drive ring 66 andretainer ring 76 may be constructed of various materials such as metaland steel.

FIGS. 6A and 6B depict another embodiment of a sleeve assembly accordingto one or more aspects of the invention. This embodiment depicts a meansof coupling or locking one or more components of a rotor bearingassembly with another member. For example, FIGS. 5A, 5B depict sleeve 48rotationally locked relative to shaft 26 without utilizing a keyway orpressed ring.

Sleeve 48 is constructed of a carbide material, such as silicon carbide.Sleeve 48 comprises an internal bore 48 a defined by a tapered internalsurface 86. A cylindrical member 88 (e.g., collet, bushing) having anouter surface 90 and an inner surface 92 forming a bore 88 a is disposedbetween sleeve 48 and shaft 26. Member 88 is a metal member in thisembodiment. Outer surface 90 is tapered surface, tapering down inthickness from one end 102 a of member 88 to the other end 102 b.Tapered outer surface 90 corresponds with internal tapered surface 86 ofsleeve 48. Member 88 forms an axial (e.g., longitudinal) slit 94 whichextends radially through member 88 from the inner surface 92 to outersurface 90 and may extend partially or entirely along the axial lengthof member 88. One or more slits 94 may be formed. For example, insteadof forming a slit 94 extending the axial length of member 88 it may bedesired to utilize one or more slits 94 that extend less than the fullaxial length of member 88. Slit(s) 94 permit member 88 to forcefullyexpand and/or contract in diameter and to provide a friction lock aroundshaft 26. According to one or more aspects of the invention sleeveassembly 49, comprising carbide sleeve 48 and member 88, may reduce theforces (e.g., loads) applied to the carbide sleeve 48. Ceramic carbidesleeve 48 is not required to deflect and does not have any stressraising notches, keyways and the like.

In the depicted sleeve assembly 49, member 88 receives shaft 26 in bore88 a and carbide bearing sleeve 48 is receives member 88 in bore 48 a(e.g., coaxially aligned with member 88). The opposing ends 102 a, 102 bof inner member 88 extend beyond the axial opposing ends of carbidebearing sleeve 48. In this embodiment, a member 96 (e.g., collar) isattached to member 88 (e.g., at end 102 b), for example via threading,adjacent to an end of sleeve 48 (e.g., the bottom end). A hole 98 a isdepicted for connecting a spanner wrench to threadedly couple collar 96to member 88. A biasing member 98 is depicted disposed between collar 96and sleeve 48. Biasing member 98 (e.g., leaf spring, Belleville spring,wave spring, etc.) maintains the fit of sleeve 48 with member 88 acrossa range of thermal contraction and expansion of the members relative toone another. According to one or more aspects of the invention, sleeveassembly 49, comprising member 88 (e.g., metal), carbide sleeve 48 andone or more of collar 96 and biasing member 98 may reduce the axialforce applied to carbide sleeve 48.

FIGS. 7A and 7B are schematic illustrations of another embodiment of arotor bearing sleeve assembly according to one or more aspects of theinvention. Bearing sleeve assembly 49 comprises an inner cylindricalmember 102 (e.g., liner, sleeve, collar, etc.) having an internal bore103 adapted for disposing the shaft and sleeve member 48 coaxiallydisposed over at least a portion of inner member 102. In the depictedembodiment, sleeve 48 is constructed of a ceramic carbide and innermember 102 is metal. Inner member 102 comprises a terminal lip 104extending radially away from bore 103. Terminal lip 104 may have a face(e.g., contoured) providing a protrusion 80 adapted to mate with a notch82 formed on sleeve member 48 which may prevent rotation of sleeve 48and inner member 102 relative to one another. In the depicted embodimenta member 96 (e.g., collar, collet) is coupled to end 102 b (e.g., bythreading) of inner member 102 distal from end 102 a and terminal lip104. Thus, inner member 102, which is metal in this embodiment, extendsbeyond the ends 47 a, 47 b of outer sleeve 48 providing a means fortransferring an axial load across ceramic carbide sleeve 48 instead ofthe axial load acting on carbide sleeve 48, for example as depicted inthe embodiment of FIG. 4. Assembly 49 depicted in FIGS. 7A and 7B mayinclude one or more features to facility attaching sleeve assembly to ashaft for example. Some examples of linking or attaching featuresinclude, without limitation, keys, keyways, hooks, threads, assembliessuch as depicted in FIGS. 5A-5B and 6A-6B.

FIGS. 8A and 8B are schematic illustrations of a ceramic carbide bearingsleeve 48 according to one or more aspects of the invention. Sleeve 48comprises an internal surface 86 defining bore 48 a and an outer surface51 which may provide rotating interface 50 with journal 36 as depictedfor example in FIG. 3. In this embodiment, a metal key 106 is providedat internal surface 86 to rotationally lock sleeve 48 to shaft 26 andkey 68 (See FIGS. 5A, 5B). In the depicted embodiment, key(s) 106 areattached to inner surface 86 by a metallurgical bond (e.g., solder,brazing, silver soldering, welding, and sintering).

Cutting a keyway into the inside diameter of sleeve 48 to engage a loosekey, which may engage a shaft keyway, creates as stress raiser. In thedepicted embodiment, one or more attachment (e.g., linking, fastening)features 106, which are depicted as keys in FIGS. 8A-8B, are attached tothe inside diameter of sleeve 48 by a metallurgical bond. Themetallurgical bond (e.g., soldering, brazing) forms a joint that issufficiently strong for the light torque that the key must transmit fromthe shaft to sleeve 48. To address the differential thermal expansion ofmetal key 106 over the axial length of sleeve 48, key 106 may beconstructed in relatively short sections. If greater shear strengthand/or greater key engagement are needed, a plurality of keys 106 may beattached to sleeve 48 to increase the shear strength and provide agreater contact between the shaft and sleeve. Metallurgical bonding ofmetal key(s) 106 to ceramic carbide sleeve 48 introduces a lower stressraiser than a keyway formed in sleeve 48 or a notch formed at an endface of sleeve 48 because it does not create an interruption in thecontinuous cylindrical surface of sleeve 48. Additionally, thisconfiguration may provide a shorter sleeve assembly and/or rotor bearingassembly than a traditional bearing assembly.

FIGS. 9A and 9B are schematic illustrations of another embodiment of asleeve according to one or more aspects of the invention. In thedepicted embodiment, sleeve assembly 49 comprises a ceramic carbidesleeve 48 coaxially receiving or carried by an inner member 102 (e.g.,liner, sleeve) constructed for example of metal. Ceramic carbide sleeve48 and metal inner member 102 may be coupled by metallurgical bonding.Internal member 102 provides an attachment feature 106 for attachingsleeve assembly 49 for example to a shaft 26 (e.g., FIGS. 3, 4, 5A, 5B)for transmission of torque. In the depicted embodiment, attachmentfeature 106 is a keyway for engaging a key 107 which is coupled to shaft26. Depicted key 107 is a loose key disposed in keyway 106 of sleeveassembly 49 and keyway 68 of shaft 26. Other examples of attachmentfeatures 106 include, without limitation, a keys, lugs, holes, threads,and hooks. For example, attachment feature 106 may be a metal keyattached to inner member 102 or formed by inner member 102. In thedepicted embodiment of FIGS. 9A-9B, ends 102 a, 102 b of inner member102 extend beyond the ends of sleeve 48 for example to transmit axialloads around sleeve 48.

The depicted embodiment further depicts grooves 108. Scoring ceramiccarbide sleeve 48 for example to form grooves 108 may promote controlledcracking of sleeve 48. In another embodiment, described with referenceto FIGS. 9A-9B, sleeve 48 comprises a plurality of ceramic carbide tiles112 attached to inner member 102 for example by metallurgical bonding ornon-metallurgical connections. The plurality of tiles 112 may alleviatecracking and breaking up compared to a monolithic ceramic carbidecomponent due to thermal expansion and contraction or deflection underload.

The inner metal member may comprise strain relief features to alleviateproblems, due to differential thermal expansion for example, by allowingthe metal member 102 to yield in one direction while retaining itsstrength in another direction. For example, a metal sleeve or liner mayinclude axial slits 94 (e.g., slots) as depicted in FIGS. 6A-6B.Referring to FIG. 10, relief features 110 are depicted formed throughinner metal member 102. In the embodiment depicted in FIG. 10, relieffeatures 110 are not formed through ceramic carbide sleeve 48.

Metal alloys that are commonly used in electric submersible pumps have acoefficient of thermal expansion (“CTE”) significantly higher than thatof ceramic carbide materials used in bearing components. The CTE(microinches/in/F) of tungsten carbide is 3.9, while alloy steels rangefrom about 6.3 to 8.3 (e.g., Monel is 7.8 and Inconel is 6.4). Thisdifferential CTE can lead to cracking or spalling of the carbide. Toalleviate such problems, the metal components can be made, for example,of iron-nickel or iron-nickel-cobalt alloys having CTE's more closelymatching the CTE of the ceramic carbide members.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the invention.The features and/or aspects of the depicted embodiments are provided forpurposes of illustration and description, therefore it will berecognized by those skilled in the art that various features and aspectsof the depicted embodiments may be combined with one another in mannersnot illustrated. Those skilled in the art will appreciate that they mayreadily use the disclosure as a basis for designing or modifying otherprocesses and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art will also realize that such equivalentconstructions do not depart from the spirit and scope of the invention,and that they may make various changes, substitutions and alterationsherein without departing from the spirit and scope of the invention. Thescope of the invention should be determined only by the language of theclaims that follow. The term “comprising” within the claims is intendedto mean “including at least” such that the recited listing of elementsin a claim are an open group. The terms “a,” “an” and other singularterms are intended to include the plural forms thereof unlessspecifically excluded.

CONCLUSION

Although exemplary systems and methods have been described in languagespecific to structural features or techniques, the subject matterdefined in the appended claims is not necessarily limited to thespecific features or acts described. Rather, the specific features andacts are disclosed as example forms of implementing the claimed systems,methods, and structures.

The invention claimed is:
 1. A bearing assembly for use with a shaft ofa pump, comprising: a carbide sleeve having an internal surface forminga bore that defines an axis and having a curved, contoured notchdisposed in a first end of the carbide sleeve; and a metal sleevedisposed at least partially within the bore of the carbide sleeve, themetal sleeve having a protrusion with a curved, contoured surface forengagement with the curved, contoured notch of the carbide sleevewherein, in an engaged state of the curved, contoured notch and thecurved, contoured surface, rotation of the carbide sleeve and the metalsleeve relative to one another generates an axial contact force.
 2. Thebearing assembly of claim 1, further comprising a lip or collar of themetal sleeve to support or transfer a compressive axial load of anadjacent component on the shaft through the metal sleeve.
 3. The bearingassembly of claim 1, further comprising a plurality of relief featuresin the metal sleeve.
 4. The bearing assembly of claim 1 wherein thecarbide sleeve comprises a plurality of the curved, contoured notchesand wherein the metal sleeve comprises a plurality of the curved,contoured surfaces.
 5. The bearing assembly of claim 4 wherein thecarbide sleeve comprises two of the curved, contoured notches andwherein the metal sleeve comprises two of the curved, contouredsurfaces.
 6. The bearing assembly of claim 1 wherein the metal sleevecomprises an axial length that exceeds an axial length of the carbidesleeve.
 7. The bearing assembly of claim 1 wherein the carbide sleevecomprises a ceramic sleeve.
 8. The bearing assembly of claim 1 whereinthe metal sleeve comprises a lip that limits axial movement of thecarbide sleeve with respect to the metal sleeve.
 9. The bearing assemblyof claim 8 wherein the lip comprises a contoured surface that limitsrotation of the carbide sleeve and the metal sleeve relative to oneanother.
 10. An electric submersible pump comprising: an electric motorthat comprises a shaft; a protector operatively coupled to the electricmotor; a pump operatively coupled to the shaft; and a bearing assemblyfor the shaft that comprises a carbide sleeve that comprises an internalsurface forming a bore that defines an axis and a curved, contourednotch disposed in a first end of the carbide sleeve; and a metal sleevedisposed at least partially within the bore of the carbide sleevewherein the metal sleeve comprises a protrusion that comprises a curved,contoured surface for engagement with the curved, contoured notch of thecarbide sleeve wherein, in an engaged state of the curved, contourednotch and the curved, contoured surface, rotation of the carbide sleeveand the metal sleeve relative to one another generates an axial contactforce.
 11. The electric submersible pump of claim 10 wherein the metalsleeve comprises a lip that limits axial movement of the carbide sleevewith respect to the metal sleeve.
 12. The electric submersible pump ofclaim 11 wherein the lip limits rotation of the carbide sleeve and themetal sleeve relative to one another.